This invention relates to electrical sockets, and more particularly to a frame type electrical socket for connecting leadless integrated circuit packages to a printed circuit board.
There is an electronic component known as a leadless integrated circuit package which is used to house large scale integrated circuit devices. This type of package is typically in the form of a thin rectangular substrate having a plurality of conductive areas or pads which are spaced along the edges of the substrate. Many prior art electrical sockets have been devised for electrically connecting this type of package to a printed circuit board.
The socket of the class to which this invention relates employs a base in the form of a frame which has a cavity in the top surface thereof designed to receive the leadless integrated circuit package. A plurality of pressure type electrical contacts is mounted along the periphery of the cavity. The leadless integrated circuit package is mounted within the cavity with the conductive pads of the package facing the pressure contacts. A cover is then placed over the integrated circuit package and fastened to the frame. The cover provides pressure on the backside of the integrated circuit package, causing the conductive pads to compress the pressure contacts and to form a gas tight contact. The pressure contacts mounted within the frame are designed so that one end of each of these contacts projects below the bottom surface of the frame, forming a second set of pressure contacts which may be used to mate with conductive pads on a printed circuit board. Thus, by fastening the frame to a printed circuit board, electrical contact is established between the conductive pads on the integrated circuit package and the conductive pads on the printed circuit board.
Some of the prior art sockets described above are designed so that the individual contacts are inserted into the frame after the frame has been formed by means such as molding. As shown in Scheingold et al U.S. Pat. Nos. 3,877,064 and 3,940,786, issued Apr. 8, 1975 and Feb. 24, 1976, respectively, this type of socket design requires the frame to be fabricated with means for retaining the individual contacts after they are inserted. The contacts themselves must be formed into an intricate shape such as the S pattern shown in the Scheingold references to both provide the required pressure contact and to engage the retaining means in the frame. The contacts must also be properly oriented before they are inserted into the frame.
Generally, frame type sockets employing insertable contacts are larger and more difficult and costly to assemble than those sockets employing molded-in contacts. In addition, insertable contacts do not possess the strength or ruggedness of molded-in contacts. One advantage, however, of insertable contacts is that a damaged contact may be replaced without the need for discarding the entire frame.
Other prior art sockets of the class to which this invention relates employ contacts which are molded into place along the periphery of the frame at the same time that the frame is formed. This type of construction, known as insert molding, requires that each contact be preformed prior to assembly to form a pressure contact. Such preforming generally necessitates that the contacts be handled one at a time and be carefully inserted into a mold in the proper orientation. This method of assembly is extremely time consuming and expensive. Further, if a contact should become damaged, the entire socket including the frame must be discarded since there are no means for replacing damaged contacts. An example of this type of socket is shown in Cutchaw U.S. Pat. No. 4,063,791, issued Dec. 20, 1977. Cutchaw shows pressure type contacts which are formed into a generally U-shape at either end to provide a pressure contact.
Accordingly, it is an object of the present invention to provide a new and improved electrical socket for leadless integrated circuit packages.
It is another object of the present invention to provide a socket having molded-in contacts and where the contacts may be formed to provide a pressure contact after they are molded in place.
It is a further object of the present invention to provide a socket having molded-in contacts and where damaged contacts may be replaced without discarding the frame portion of the socket.